xen/tools/firmware/hvmloader/32bitbios_support.c

/*
 * 32bitbios_support.c - relocation of 32bit BIOS implementation
 *
 * Stefan Berger, stefanb@us.ibm.com
 * Copyright (c) 2006, International Business Machines Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 */
#include <elf.h>
#include <xen/hvm/e820.h>
#include "util.h"
#include "config.h"

#include "../rombios/32bit/32bitbios_flat.h"
#include "../rombios/32bit/jumptable.h"


/*
 * relocate ELF file of type ET_REL
 */
static int relocate_elf(unsigned char *elfarray) {
    Elf32_Ehdr *ehdr = (Elf32_Ehdr *)elfarray;
    Elf32_Shdr *shdr = (Elf32_Shdr *)&elfarray[ehdr->e_shoff];
    int i;

    if (ehdr->e_type != ET_REL) {
        printf("Not a relocatabel BIOS object file. Has type %d, need %d\n",
               ehdr->e_type, ET_REL);
        return -1;
    }

    for (i = 0; i < ehdr->e_shnum; i++) {
        if (!(shdr[i]).sh_flags & SHF_ALLOC) {
            shdr[i].sh_addr = 0;
            continue;
        }
        shdr[i].sh_addr = (Elf32_Addr)&elfarray[shdr[i].sh_offset];
    }

    for (i = 0; i < ehdr->e_shnum; i++) {
        if (shdr[i].sh_type == SHT_REL && shdr[i].sh_addr != 0) {
            Elf32_Shdr *targetsec = (Elf32_Shdr *)&(shdr[shdr[i].sh_info]);
            Elf32_Shdr *symtabsec = (Elf32_Shdr *)&(shdr[shdr[i].sh_link]);
            Elf32_Sym  *syms      = (Elf32_Sym *)symtabsec->sh_addr;
            Elf32_Rel  *rels      = (Elf32_Rel *)shdr[i].sh_addr;
            unsigned char *code   = (unsigned char *)targetsec->sh_addr;
            int j;

            for (j = 0; j < shdr[i].sh_size / sizeof(Elf32_Rel); j++) {
                int idx           = ELF32_R_SYM(rels[j].r_info);
                Elf32_Sym *symbol = &syms[idx];
                uint32_t *loc     = (uint32_t *)&code[rels[j].r_offset];
                uint32_t fix      = shdr[symbol->st_shndx].sh_addr +
                                    symbol->st_value;

                switch (ELF32_R_TYPE(rels[j].r_info)) {
                    case R_386_PC32:
                        *loc += (fix - (uint32_t)loc);
                    break;

                    case R_386_32:
                        *loc += fix;
                    break;
                }
            }
        } else if (shdr[i].sh_type == SHT_RELA) {
            return -2;
        }
    }
    return 0;
}

/* scan the rombios for the destination of the jumptable */
static char* get_jump_table_start(void)
{
    char *bios_mem;

    for ( bios_mem = (char *)ROMBIOS_BEGIN;
          bios_mem != (char *)ROMBIOS_END;
          bios_mem++ ) {
        if (strncmp(bios_mem, "___JMPT", 7) == 0)
            return bios_mem;
    }

    return NULL;
}

/* copy relocated jumptable into the rombios */
static int copy_jumptable(unsigned char *elfarray)
{
    int rc = 0;
    Elf32_Ehdr *ehdr = (Elf32_Ehdr *)elfarray;
    Elf32_Shdr *shdr = (Elf32_Shdr *)&elfarray[ehdr->e_shoff];
    Elf32_Shdr *shdr_strings = (Elf32_Shdr *)&shdr[ehdr->e_shstrndx];
    char *secstrings = (char *)&elfarray[shdr_strings->sh_offset];
    uint32_t *rombiosjumptable = (uint32_t *)get_jump_table_start();
    uint32_t *biosjumptable    = NULL;
    int i;

    if (rombiosjumptable == NULL) {
        return -3;
    }

     /* find the section with the jump table  and copy to lower BIOS memory */
    for (i = 0; i < ehdr->e_shnum; i++) {
        if (!strcmp(JUMPTABLE_SECTION_NAME, secstrings + shdr[i].sh_name)) {
            uint32_t biosjumptableentries;
            biosjumptable        = (uint32_t *)shdr[i].sh_addr;
            biosjumptableentries = shdr[i].sh_size / 4;
            for (int j = 0; j < biosjumptableentries; j++) {
                rombiosjumptable[j] = biosjumptable[j];
                if (biosjumptable[j] == 0 &&
                    j < (biosjumptableentries - 1)) {
                    printf("WARNING: jumptable entry %d is NULL!\n",j);
                }
            }
            break;
        }
    }

    if (biosjumptable == NULL) {
        printf("Could not find " JUMPTABLE_SECTION_NAME " section in file.\n");
        rc = -4;
    }

    return 0;
}

static int relocate_32bitbios(unsigned char *elfarray, uint32_t elfarraysize)
{
    int rc = 0;
    uint32_t mask = (64 * 1024) - 1;
    uint32_t to_malloc = (elfarraysize + mask) & ~mask; /* round to 64kb */
    unsigned char *highbiosarea;

    highbiosarea = (unsigned char *)(long)
                           e820_malloc((uint64_t)to_malloc,
                                       E820_RESERVED,
                                       (uint64_t)0xffffffff);

    if (highbiosarea != 0) {
        memcpy(highbiosarea, elfarray, elfarraysize);
        rc = relocate_elf(highbiosarea);
        if (rc == 0) {
            rc = copy_jumptable(highbiosarea);
        }
    } else {
        rc = -5;
    }

    return rc;
}

int highbios_setup(void)
{
    return relocate_32bitbios((unsigned char *)highbios_array,
                              sizeof(highbios_array));
}